At least six people were taken to area hospitals Saturday night from a weekend music festival in Humboldt Park.
It happened while the rock band “Blink 182″ was on stage.
Chicago Fire Dept officials had requested 10 ambulances to be stationed at Riot Fest as a precautionary move.
Firefighters say several people suffered anxiety attacks, and a few people were trampled.
They transported four people in good-to-fair condition and two in fair-to-serious condition.
Police officials said the people sustained various minor injuries.